Accessory Navicular bone – Foot

File:Accessory and cornuate navicular bone on dorsoplantar X-ray - annotated.jpg

The accessory navicular (os navicularum or os tibiale externum) is an extra bone or piece of cartilage located on the inner side of the foot just above the arch. It is embedded in the tibialis posterior tendon  

It is congenital and is present from birth in individuals who have it.

It is a common condition frequently asked in various examinations like NEET/USMLE/AMC/PLAB

What Is Accessory Navicular Syndrome?

Some of the people who have accessory navicular can have this condition resulting form accessory navicular bone and can be very painful due to following reasons:

  • Trauma to the foot or the ankle
  • Chronic irritation from shoes or other footwear rubbing against the extra bone
  • Excessive activity or overuse
     

Many people with accessory navicular syndrome also have flat feet (fallen arches). Having a flat foot puts more strain on the posterior tibial tendon, which can produce inflammation or irritation of the accessory navicular.

Signs & Symptoms of Accessory Navicular Syndrome

The signs and symptoms of accessory navicular syndrome include:

  • A visible bony prominence on the midfoot (the inner side of the foot, just above the arch)
  • Redness and swelling of the bony prominence
  • Vague pain or throbbing in the midfoot and arch, usually occurring during or after periods of activity
     

Diagnosis

Clinical examination will suggest accessory navicular where it can be palpated against the tibialis posterior tendon on the medial arch of the foot.

X-rays are usually ordered to confirm the diagnosis. If there is ongoing pain or inflammation, an MRI or other advanced imaging tests may be used to further evaluate the condition.

Nonsurgical Treatment Approaches

Symptomatic relied is provided first before considering surgery. The following may be used:

  • Immobilization. Placing the foot in a cast or removable walking boot allows the affected area to rest and decreases the inflammation.
  • Ice. To reduce swelling, a bag of ice covered with a thin towel is applied to the affected area. Do not put ice directly on the skin.
  • Medications. Oral nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, may be prescribed. In some cases, oral or injected steroid medications may be used in combination with immobilization to reduce pain and inflammation.
  • Physical therapy. Physical therapy may be prescribed, including exercises and treatments to strengthen the muscles and decrease inflammation. The exercises may also help prevent recurrence of the symptoms.
  • Orthotic devices. Custom orthotic devices that fit into the shoe provide support for the arch and may play a role in preventing future symptoms.
     

Even after successful treatment, the symptoms of accessory navicular syndrome sometimes reappear.  When this happens, nonsurgical approaches are usually repeated.

Surgical options ?

If nonsurgical treatment fails to relieve the symptoms of accessory navicular syndrome, surgery may be appropriate. Surgery involves taking out the extra piece of bone.

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